Query : 2002A&A...389..577G

2002A&A...389..577G - Astronomy and Astrophysics, volume 389, 577-588 (2002/7-2)

The threaded molecular clumps of Chamaeleon III.


Abstract (from CDS):

We have mapped large areas in the Chamaeleon III complex of molecular clouds with the SEST in 13CO(J=1-0) and in C18O(J=1-0). The stronger CO emission coincides with areas of cold dust emission, which is distributed in long, but thin, wavy filaments. We identify some 40 clumps of enhanced CO emission in these filaments. In the southern part of Cha III the clumps are equidistant along the main zig-zag shaped filament. Here we find two systems of filaments moving at different radial velocities. At least part of the zig-zag patterns visible on optical images may be caused by overlapping filaments. All clumps are small (typically 0.02-0.05pc in radius), and of small mass (typically 0.1-0.7M, when assuming the ``standard'' C18O/H2 column density ratio). Also the average number densities are small, n(H2)=1x104-8x104cm–3, and the density contrast between clump and interclump gas is only ∼10. In addition the values of |Epot|/Ekin are unusually small, 0.03-0.33. These clumps have smaller masses than those so far identified in other molecular clouds. Previously reported clumps of larger masses in Cha III turn out to be composed of assemblies of clumps. There are no signs of star formation in Cha III (unlike Cha I and Cha II), and our results indicate also that such activity is not expected. However, with the velocity dispersion of 0.2km/s the clumps would leave the thin filaments on short timescales, and if the clumps as such are not confined by some external force, they would also lose their identity on even shorter timescales. We discuss the possibility that the clumps are confined by electromagnetic forces, and show that this may work with reasonable assumptions on the required magnetic field strength. We also discuss the possibility that the clumps are attached to magnetic ropes along the filamentary axis, in which case the clumps could swing back and forth perpendicularly to the axis, like they were threaded on elastic strings.

Abstract Copyright:

Journal keyword(s): ISM: clouds - ISM: structure

Nomenclature: Fig.1: [GLC2002] Cha III-A (Nos A-F). Table 1: [GLC2002] Cha III-A a (Nos a-b), [GLC2002] Cha III-B a (Nos a-s), [GLC2002] The Serpentine a (Nos a-q).

Status at CDS : All or part of tables of objects will not be ingested in SIMBAD.

Simbad objects: 12

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Number of rows : 12
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
1 NAME Cha 1 MoC 11 06 48 -77 18.0           ~ 1099 1
2 NAME Chamaeleon Region SFR 11 55 -78.0           ~ 766 0
3 NAME Musca Cld 12 23 -71.3           ~ 203 0
4 NAME Coalsack Nebula DNe 12 31 19 -63 44.6           ~ 252 0
5 IRAS 12340-7958 LP* 12 37 39.7408011816 -80 15 13.707391932   16.11 14.39 13.63 9.81 ~ 106 0
6 NAME Cha III MoC 12 37.8 -80 15           ~ 136 2
7 NAME Thumbprint Nebula DNe 12 44 55.6 -78 48 16           ~ 22 0
8 NAME Cha II MoC 12 54 -77.2           ~ 323 0
9 NAME Loop I SR? 15 01 -38.7           ~ 367 2
10 NAME Upper Sco-Cen As* 16 15 -24.2           ~ 1275 1
11 NAME Local Bubble ISM ~ ~           ~ 833 0
12 NAME the Serpentine in Cha III PoC ~ ~           ~ 1 0

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